Many types of fluid transport systems exist which require tubing to transport fluid between points in a system. Fluid diffusion is a problem in such systems, particularly in closed systems, whether the losses are due to water vapor transmission or the loss of the fluid components of a mixture. For example, if three components form a fluid mixture and each component has a different diffusion rate or permeability rate, then the concentration ratio of these components will shift over time due to the high diffusion rates in known tubing.
Another example of this problem arises in the field of cooling systems for electronics. Within this field there is the need to cool semiconductor chips. As this need grows it is presenting significant challenges to traditional designs. Moreover, modern high performance processors have very high heat dissipation requirements. However, the traditional cooling methods, which include fan mounted heat sinks and heat pipes, have a number of limitations. Fan mounted heat sinks often do not move air quickly enough to cool a modern processor, or do not sufficiently move hot air out of the casing holding the electronics. Similarly, heat pipes are limited in the amount of heat they can dissipate, and the distance they can move the heat from the heat source. Hence, conventional cooling techniques that use heat pipes or fan mounted heat sinks are not adequate for cooling modern electronics, such as high performance processors.
Systems that use liquid coolant are effective in cooling a semiconductor chip which generates significant heat. Such liquid cooling systems require the use of tubing to transport fluid. Examples of such cooling systems are further described in U.S. Pat. No. 7,000,684, and U.S. Provisional Patent Application No. 60/788,545, entitled “Multi-Chip Cooling”, which are incorporated herein by reference. In such systems, fluid travels through tubing to dissipate heat generated by semi-conductors.
In these systems, a vapor concentration gradient exists across the tubing boundary. Under cooling condition, the heated coolant dissipates through the walls of the tubing because there is a low concentration on the other side of the tubing. Diffusion continues to be driven by this gradient until substantial equilibrium is established on both sides of the inner tubing and the vapor concentration gradient becomes substantially zero.
Diffusion of vapor in a liquid cooling system is a problem, and potentially catastrophic if the system is allowed to dry up. In a liquid cooling system that uses a radiator, the loss of fluid results in a gradual loss of thermal performance. Furthermore, in a liquid cooling system where fluid is pumped, the substantial loss of fluid eventually results in overheating.
One solution to the problem of vapor loss is to use tubing that is known to have low water vapor transmission rates. An example of such tubing is metal tubing. The use of such tubing presents design challenges due to its rigid nature, the expense of metal, and the difficulty in assembly. Furthermore, any mixing of metals in such a system leads to corrosion and clogging in the tubes, pump or radiator.
What is needed is tubing with a high degree of flexibility and a very low water vapor transmission rate.